The discovery of insects as pathogens vectors was established for over a century and was the driving force behind the discipline "medical and veterinary entomology". Despite the success of some prevention and control program campaigns, the emergence and spread of vector-borne diseases occurred dramatically during this last thirty years. Bluetongue virus (BTV) (Reoviridae: Orbivirus) is a good example of emerging virus in Europe, with a little understanding of the epidemiology of this disease. This virus is transmitted by blood-sucking midges of the genus Culicoides (Diptera: Ceratopogonidae) to wild and domestic ruminants. In Europe, BT was considered an exotic disease. In 1998, several incursions appeared in the western Mediterranean Basin in line with the northward progression of C. imicola populations, the main afrotropical vector. From August 2006, the emergence and transmission of serotype 8 in northern Europe, in areas where C. imicola is absent, revealed the importance of autochthonous species and the urgent need to understand their role as vector. This work gives new insights into the understanding of BTV transmission in northern Europe: i) presenting a state of the art review of the biology and ecology of Culicoides adults, ii) assessing different methods to study the biting rate and iii) highlighting trends in host-seeking behavior.
